HOWTO: Get a Dialog to Use an Icon When Minimized

ID: Q114612

The information in this article applies to:

Microsoft Win32 Software Development Kit (SDK)
Microsoft Windows Software Development Kit (SDK) version 3.1

SUMMARY

The standard Windows dialog box does not have an icon when it is minimized. A dialog box can be made to use an icon by replacing the standard dialog box class with a private dialog box class.

MORE INFORMATION

The standard dialog box class specifies NULL as the value of the hIcon field of its WNDCLASS structure. So no icon is drawn when the standard dialog box is minimized.

An icon can be specified by getting the dialog to use a private class as follows:

1. Register a private class.

      WNDCLASS wc;

      wc.style = CS_DBLCLKS | CS_SAVEBITS | CS_BYTEALIGNWINDOW;
      wc.lpfnWndProc = DefDlgProc;
      wc.cbClsExtra = 0;
      wc.cbWndExtra = DLGWINDOWEXTRA;
      wc.hInstance = hinst;
      wc.hIcon = LoadIcon(hinst, "DialogIcon");
      wc.hCursor = LoadCursor(NULL, IDC_ARROW);
      wc.hbrBackground = COLOR_WINDOW + 1;
      wc.lpszMenuName = NULL;
      wc.lpszClassName = "MyDlgClass";
      RegisterClass(&wc);

   NOTE: The default dialog window procedure, DefDlgProc(), is used as the
   window procedure of the class. This causes windows of this class to
   behave as standard dialogs. The cbWndExtra field has to be assigned to
   DLGWINDOWEXTRA - the dialog box stores its internal state information in
   these extra window bytes. The icon to be used when the dialog box is
   minimized is assigned to the hIncon field.

2. Get the dialog box to use the private class.

   Use the CLASS statement in the dialog box template to get the dialog box
   to use the private class:

      IDD_MYDIALOG DIALOG 0, 0, 186, 92
      CLASS "MyDlgClass"
      :

3. Create the dialog box using DialogBox() or CreateDialog().

      DialogBox (hinst,
                 MAKEINTRESOURCE (IDD_MYDIALOG),
                 NULL,
                (DLGPROC)MyDlgFunc);

   MyDlgFunc() is the dialog function implemented by the application. When
   the dialog box is minimized, it will use the icon specified in the
   private class.

Additional query words:

Keywords          : kbDlg kbNTOS kbGrpUser kbWinOS 
Issue type        : kbhowto

Last Reviewed: January 2, 1999